Ok, I didnt know that. In that case the touch screen would be of
little use as I would have made a user interface with large buttons on
it that a user should be able to press with his fingers.

Actually, the screen is just a bonus, it wouldnt be necessary for the
project I was thinking of. The computing power is what interested me
first, and especially the battery life. These things claim to run for
3-4 hours and thats including the powering of the LCD screen.

The nice thing about these PC's is that I do not have to worry about
the power and all the electronics for regulating power and charging is
already there, and it would be pretty simple to create a docking
station for the robot to park for more power. I read that people say
that you should avoid Lithium-Ion batteries for robot projects as it
is to dangerous if you do not know what you are doing, charging them
in a safe place just in case they explode. Well, I do not want to take
these risks as I am more of a software guy than hardware, so I was
looking for complete powering solutions where I didnt have to worry
about these issues. NiMH batteries will add so much to the weight that
I am afraid it would bog the robot down (servos and such would then
have to be equally powerful).

Does anybody have any idea how it is to power the Mini-ITX systems
with a Lithium-Ion battery of around 3800 mAh as most of these
portable pc's use? They have a calculator at [url]www.mini-box.com[/url] that
show me around 36watts drain when running a configuration with two USB
devices and one 2.5" HD in playing DVD mode. I would assume my robot
would be running 100% CPU almost all the time, busy with its vision
processing all the time. How do I go about calculating how long a 3800
mAh battery would last on this? (I am sorry if I am reapeating myself,
but maybe someone have a quick answer to this).

Thank you.

> A Tablet PC is not a touch screen. It has an electrostatic display that
> pulses an energy field across the entire screen very rapidly that energizes
> a small capacitor in the stylus (the pen), when the pulse goes away, the cap
> discharges powering a small circuit of some sort which emits some kind of
> 'becon' that the PC uses to know where the been is. Touching the screen with
> your hand has no effect on anything. Its like this so you can rest your hand
> on it and write without activating anything. The stylus will move the cursor
> even though it is not touching the screen.
>
> Now if you dont mind using the stylus to touch things on the screen, then
> this will do the trick. Otherwise, I suggest sticking to a miniITX and a
> stand alone touch screen LCD.
>

Ok, I have done some more researching and a typical Mini-ITX system
would run for about 12 hours on a 7 Amp SLA battery which would give
it a mAh/kg ratio of 2641 mAh/kg. These numbers are based on BB's
BP7-12 battery. Its still a heavy battery for a robot 2.65 kg although
these batteries are cheap. I want to reduce the weight as much as
possible as there will be times the robot needs to lift itself up to
e.g. climb stairs or similar obstacles in a home (typically this would
be an issue going through doors too).

Some more research I found 12 volt 3300 mah NiMH at a robot webstore
that has weight of 0,62 kg resulting in a ratio of 5322 mAh/kg. So a
doubling in power per kg. Two of these would give me 6,6 Amps and
around 10-12 hours operating time on the Mini-ITX with some USB
devices and a 2.5" harddrive.
Of course, the servos and motors would also draw some power from this
probably halving this again I would expect. Still around 5 hours of
operating time on a 1 kg NiMH battery system seems acceptable to me.
If the robot has the torque I could always add another pack and maybe
get a full day of operating time.

Now the next challenge is where to find a good system where the robot
could dock and charge the NiMH battery when it is close to depleted.
This would require my robot to measure when the voltage is dropping?
Anyone have any information on this? Something that can interface
simply with a digital input on a controller. It would also be nice if
the robot could draw its power from the "docking bay" charger while it
fills up its battery so that it is still operating. Is this difficult
to achieve including the safety needed so I dont fry the thing?

Any help appreciated. Thanks!